The electronics, display and energy industries rely on the formation of coatings and patterns of conductive and other electronically active materials to form circuits on organic and inorganic substrates. The primary methods for generating these patterns are screen printing for features larger than about 100 μm and thin film and etching methods for features smaller than about 100 μm. Other subtractive methods to attain fine feature sizes include the use of photo-patternable pastes and laser trimming.
It is the trend in the electronics industry to make smaller and less expensive electronic devices that provide higher resolution and enhanced display performance. As a result, it has become necessary to develop new materials and new approaches to manufacture such devices.
The ink jet printing system is a high resolution, additive printing system having the ability to print complex patterns through digital instructions. This ink jet printing system is a recording system, which prints by discharging ink drops through a discharge orifice such as a nozzle or a slit to thus make the ink drops directly adhere to a printing substrate. Ink jet techniques usually fall into two broad categories: continuous injection systems and on-demand systems. In continuous injection systems, the ink jet is firing a continuous stream of microdrops and the pattern is established by selectively diverting, or not diverting, the microdrops to a waste reservoir. This system cannot be viewed as fully additive in that the portion of material diverted to the reservoir is lost, making the process less than 100% additive. In the on-demand system, drops are fired only when required. These systems are more prone to clogging when employing inks with high solids content, and it is a common feature that the first several drops on demand may not be ejected as expected.
Ink jet printing is at its optimal utility when small complex patterns are required. By its nature, using picoliter drops at a time, the process is slow for patterns where large features requiring large quantities of ink are desired.
At times it will be preferable to coat an entire substrate with a surface layer and then in a subtractive process, etch away the undesired portion of the image. On the nano-scale, this is one of the fundamental underlying processes of the semiconductor industry. Their technology is aggressive and well suited to small devices but there are many instances where the resolution of the semiconductor industry is not required. The selective removal of material in a digitally-controlled pattern is desired. This is often done by laser ablation, but the technique is difficult when the underlying material is thermally sensitive and particularly difficult when the layer to be removed is transparent and the layer below it to be left is opaque.
A technique to selectively etch portions of one layer while not damaging the subsequent underlayer will find utility in a wide variety of applications. Ink jet printing of etchants that will selectively remove or ink jet printing of modifiers that will selectively transform a layer of material without damaging the underlying layer provides a highly useful method for the design of electronic or photonic circuits, ornamental patterns, photovoltaic devices and a variety of other useful systems.
Despite the advances in such systems, the multiple, time-intensive steps required for current etching techniques employing resists are a limitation to manufacturing. Manufacturers are continuously seeking improved techniques and compositions that can fulfill their needs for selective materials removal. The techniques may be used in very specific applications if they provide greater speed and more specific materials removal. Such materials can increase the speed of the manufacturing processes without compromising high resolutions in the lines and spaces of the circuit or display patterns. The present invention is directed to such processes, materials and compositions suitable for implementation of the processes, and methods for production of the materials.